A Review of Applications, Prospects, and Challenges of Proton-Conducting Zirconates in Electrochemical Hydrogen Devices

Abstract

In the future, when fossil fuels are exhausted, alternative energy sources will be essential for everyday needs. Hydrogen-based energy can play a vital role in this aspect. This energy is green, clean, and renewable. Electrochemical hydrogen devices have been used extensively in nuclear power plants to manage hydrogen-based renewable fuel. Doped zirconate materials are commonly used as an electrolyte in these electrochemical devices. These materials have excellent physical stability and high proton transport numbers, which make them suitable for multiple applications. Doping enhances the physical and electronic properties of zirconate materials and makes them ideal for practical applications. This review highlights the applications of zirconate-based proton-conducting materials in electrochemical cells, particularly in tritium monitors, tritium recovery, hydrogen sensors, and hydrogen pump systems. The central section of this review summarizes recent investigations and provides a comprehensive insight into the various doping schemes, experimental setup, instrumentation, optimum operating conditions, morphology, composition, and performance of zirconate electrolyte materials. In addition, different challenges that are hindering zirconate materials from achieving their full potential in electrochemical hydrogen devices are discussed. Finally, this paper lays out a few pathways for aspirants who wish to undertake research in this field.

Keywords: electrochemical device; hydrogen pumps; hydrogen sensors; perovskite oxide; proton-conducting oxide; tritium monitoring; tritium recovery; zirconate.

Figure 1

An outline of the main points of this review shown schematically.

Figure 2

The fundamental design and operation of a proton-exchange membrane (PEM)-based electrochemical hydrogen device. Reprinted with permission from Ref. [68]. Copyright 2019 Elsevier.

Figure 3

A schematic representation of the tritium monitor in combination with the proton-conducting material. Reprinted with permission from Ref. [70]. Copyright 2004 Taylor & Francis.

Figure 4

(a) Change in hydrogen evolution rate with time for different electrode combinations, (b)Time series response of current (top panel), water vapor concentration at the anode outlet (middle panel), and hydrogen concentration (bottom panel) against enrichment characteristics. Reprinted with permission from Ref. [71]. Copyright 2006 Elsevier.

Figure 5

(a) Change in tritium concentration and hydrogen recovery rate with water vapor partial pressure, (b) relationship between the tritium concentration in anode compartmented the estimated tritium concentration. Reprinted with permission from Ref. [69]. Copyright 2015 Taylor & Francis.

Figure 6

(a) A schematic representation of hydrogen extraction system with proton-conducting ceramic on one end, (b) response of hydrogen evolution rate (top panel) and hydrogen, methane, and water vapor concentration (bottom panel) as a function of current. Reprinted with permission from Ref. [93]. Copyright 2004 Taylor & Francis.

Figure 7

SEM of electrode surface; (a) pasted electrode (a magnification of ×10,000), (b) plated electrode (a magnification of ×10,000) and (c) plated electrode (a magnification of ×50,000). Reprinted with permission from Ref. [81]. Copyright 2004 Taylor & Francis.

Figure 8

(a) Hydrogen evolution rate versus current under various temperatures, (b) The hydrogen evolution rate, and efficiency as a function of current (gas mass flow rates). Reprinted with permission from Ref. [80]. Copyright 2014 Elsevier.

Figure 9

(a) Schematic of H₂ sensor with a sintered CaZr_0.9In_0.1O_3−δ (b) Experimental setup for hydrogen sensor in various partial pressure gases. Reprinted with permission from Ref. [89]. Copyright 2016 Elsevier.

Figure 10

Chemical composition of materials and the schematic of the fabrication process of the hydrogen sensor. Reprinted with permission from Ref. [83]. Copyright 2012 Elsevier.

Figure 11

(a) Operating principle of steam electrolysis cells based on proton-conducting electrolytes (b) SEM images of the cross section of SCYb interlayer SZCY-541 electrolyte (top), SCYb interlayer (middle) and nickel electrode (bottom) (c,d) hydrogen evolution rate of the steam electrolysis cell with SZCY-541 electrolyte, SSC-55 anode, nickel cathode and SCYb interlayer at 800 °C (c) and 600 °C (d). Reprinted with permission from Ref. [112]. Copyright 2009 Elsevier.

Figure 12

(a) Variation of current density and gas concentrations at the outlet of the anode and cathode as a function of applied voltage, (b) gas concentration change at the outlet as a function of temperature; here hydrogen, methane, carbon monoxide, carbon-di oxide, and water vapor are shown. Reprinted with permission from Ref. [97]. Copyright 2010 Elsevier.

Figure 13

Time evolution of hydrogen and water vapor at the cathode outlet under the wet atmosphere containing oxygen; (a) applied voltage and current, (b) concentration of water vapor and hydrogen. Reprinted with permission from Ref. [97]. Copyright 2005 Taylor & Francis.